Fuel pump



May 1933- M. HOFMANN 1,909,961

FUEL PUMP Filed Dec. 11, 1929 3 Sheets-Sheet l 4 77067 wi ffi essx Max H0 777a 7771 M. HOFMANN May 23, 1933.

FUEL PUMP 5 Sheets- -Sheet 2 Filed Dec. 11, 1929 4770a???- MarHa/m anrz M. HOFMANN- May 23, 1933.

FUEL PUMP Filed Dec 11, 1929 v 3 Sheets-Sheet 3 Evy Patented May 23, 1933 vention will appear from the detailed de- UNITED STATES.

PATENT OFFICE MAX HOFMANN, or WAUKESHA, WISCONSIN, ASSIGNOR r0 wnvxnsm heron comrm, or WAUKESHA, WISCONSIN, A CORPORATION or wxsconsnv,

- FUEL PUMP I 4 7 Application filed December 11, 1929. Serial No. 413,196.

This invention relates to fuel pumps, and more particularly to a pump for supplying fuel under pressure to the injection nozzles of injection engines.

One of the main objects of my invention is j to provide a pump of the character stated having improved plunger operating means whereby increased efliciency' in operation of the pump is obtained.

Another object is to provide simple and efficient means for'regulating accurately the measured quantity of fuel which is discharged from the pump to the tube leading to the injection nozzle.

A further object is to provide means for suitably connecting the fuel supply tube of the nozzle to the outlet of the pump. in such a manner as to avoid necessity of varying the interior diameter of the tube, thus assuring more uniform flow of the fuel from the pump to the injection nozzle.

Further objects and advantages of my inscription.

In the drawings: 7 Figure 1 is a side view of a pump constructed in accordance with my invention, the pump casing being shown in section;

Figure 2 isa sectional view taken substantially on the line 22 of Figure 1, parts being shown in elevation;

Figure 3 is a diagram of the timing of the valves and the pump plunger when the valves are set for maximum injection;

Figure 4 is a section through the pump,

a block taken substantially on line 44 of Fig- Figure 5 is a fragmentary end view of the pumpicasing, looking from the rear thereof, showing the means for adjusting the rocker levers of the. suction valves;

I jection nozzle,-the nozzle being shown fragmentarily..

I have illustrated my pump as mounted in a suitable casing comprising a lower section 1 and a removable cover 2 therefordetachably secured to section 1 in a suitable man ner. Casing section 1 is provided, at each end thereof, with an upper flange 3 upon which seats an end extension 4- of a pump block 5, these extensions being suitably secured to flanges 3, as by bolting. This block is bored out from one end thereof to provide a spill passage 6 disposedadjacent one side of the block, and a supply passage 7 and a foaming passage 8 adjacent the other side of the block. Passage 7 is connected by a tube 9a to a suitable source of supply of fuel oil,

or other suitable liquid fuel, suchas a tank,-

a the block is interiorlythreaded at the end portions of this opening. A sleeve 10, provided at its lower end with a reduced threaded neck 11, screws into the upper end of the opening or bore above chamber 9, and a gasket 12 is interposed between this sleeve and a shoulder formed in the block about the opening to effect a fluid tight and pressure resistant closure between the sleeve and the block. I

Sleeve 10 is interiorly threaded from its upper end to within a short distance of its lower end, and neck 11 is provided with a reduced bore 13 leading from the bore of the sleeve, and with an outlet port l opening from bore.13 into pump chamber.'9.- The lower end of bore 13 is tapered toward port 14"to provide a seat for ball check valve 15 normally held seated'by-a spring 16' confined between the ball check valve and a downwardly tapering boss 17 of a ,ring 18 which fits within the lower unthreaded portion of the bore of sleeve 10. The opening of this ring is in alignment with bore 13 and the under face of boss 17 is rounded soas to seat ac-- curately in the upper end ofvbor e 13, which *jection nozzle of an injection engine.

is slightly flared at its upper end for. this purpose. A pressure ring 19, provided with slots 20 for reception of elements of a suitable tool, screws into sleeve 10 and serves to secure ring 18 accurately in position when tubing 22 is being assembled or disassembled. Ring 19 is provided with a central bore of proper size to snugly receive the lower end of a fuel supply tube 22 for conducting the fuel under pressure from the pump to an e ring 18 projects inwardly beyond the bore of ring 19, radially thereto, so as to extend beneath the lower end of tube 22, which seats upon the upper face of ring 18.

Thimble 23 is threaded and brazed or' otherwise suitably secured upon tube 22 and is provided, at its lower end, with an outer shoulder. 24 slidable within sleeve 10. The upper face of this shoulder is inclined downwardly and outwardly of the sleeve and a clamp nut 25 fits about thimble 23 and screws into the sleeve, the surface at the lower end of this nut being inclined downwardly and outwardly of the sleeve for contact with the inclined shoulder of the thimble. By turning the nut into the sleeve, tube 22 is forced downwardly so as to seat tightly upon the upper face of ring 18 and form a fluid tight fragmentarily, has a fuel inlet duct 22 which- 9'at opposite sides thereof.

closure -;therewith. The thimble and the clamp nut serve to tightly secure the tube in position and also to resist pressure to which the tube is subjected and .which might tend to move the tube away from the ring 18. This provides simple and highly eflicient means for securing the tube 22 to the pump at the discharge side thereof. while avoiding any change in the interior diameter of the tube which would be apt to affect the flow of the fuel oil therethrough' and, therefore,

' 1 would tend to interfere with accuracy of the feed offuel to the injection nozzle of the en ine.

eferring to Figure 7, the other end'of tube 22 is connected to an injection nozzle N of known type. This nozzle which is shown registers with the bore of tube 22. The nozzleis suitably bored and threaded for recep-' tion' 'ofa clamping nut 25 which bears against shoulder 24 of a thimble 23 threaded and brazed upon the tube- The tube 22 projects inwardly beyond the thimble into a recess 22" at the outer end of and concentric with duct 22. The end of the tube seats against the wall at the inner end of recess 22 and forms a subs'tantially'tight closure there-.

with. 7

Block -6 is bored'out fromthe underface and at each side thereof to provide passages 26 and 27 which open into the pump chamber 'The outer portion of the bore, the inner rtion of which forms-the passage 26, is of increased diameter and is interiorly threaded screw plugs 41.

for reception of the valve cage 28 which screws into the block. This valve cage 28 is provided with an axial bore in which is slidably mounted a valve stem 29 which carries at its upper end a valve 30 which seats in the upper end of the cage 28 and normally closes an enlarged portion 31 of the bore of cage 28. Upper portion 29a of valve stem 29 is of reduced diameter so as to provide ample space about such portion for free flow of oil past the valve 30 when this valve is open or unseated. The upper portion of valve cage 28 is of reduced diameterto provide a channel 32 about'the same, and this cage is provided with orts 33 which establish communication etween this channel and the space 31 within the cage beneath valve 30. Adjacent its inner end, cage 28. is provided with an outer annular shoulder 34, and a packing gasket 35 is confined between this shoulder and a corres onding shoulder formed in the block 5. T e valve 30 is normally held seated by an expansion coil spring 36 mounted about valve stem 29 and confined between the inner end of recess 37 in the lower end of valve cage 28, in which the spring seats, and a collar 38 suitably secured on stem 29 adjacent the outer end thereof.

The outer ends of these ducts are closed by This provides means for supplying oil to channel 32 and thence, through ports 33 to space 31 about the reduced portion 29a' of valve stem 29. The valve 30 controls the admission of'oil to pump chamber 9, through passage 26, and I term this valve the suction valve.

*A spill valve 42 controls the escape of oil from chamber 9. This spill valve is similar to, but smaller than valve 30 and is mounted in a valve cage 43 having a reduced portion about which extends a channel 44 into which 'ports 45 open from a space 46 extending above the reduced inner end portion 47a of valvestem 47. This valve'stem is urged out wardly by an expansion coil spring 48 in the same manner as stem 29 of valve 30, and a fluid tight closureis efi'ected about the valve cage 43, adjacent the inner end thereof, by means of a packing gasket and cooperating shoulders in the block and on the valve cage. Theblock 5 is bored out to provide a duct 49 which intersects passage 6"and channel 44, the 'outer end of this duct being closed by a cap screw 50. As will be noted more clearly from Figure 1, these cap screws also serve to secure an elongated U-shaped bracket'52 to block 5 at the upper face thereof;

A sleeve 53 screws into the lower enlarged pprtion of the bore which provides the-cham r9. 'Theupper end of this sleeve bears against the under face of the shoulder 54 of abushing 55, and a packing gasket 56 is interposed between the upper face of this shoulder anda corresponding shoulder formed in the block. This provides a fluid tight closure between the bushing and the block about the lower end of the pump chamber 9. A plunger 56a reciprocates in bushing 55 which, in fact, constitutes the cylinder of a pump. This plunger has a. polished finish and fits the bushing 55 snugly so as to prevent leakage of oil about the plunger. A yoke 57 is suitably secured on the lower end of plunger 56a and is connected by a pin 58 to an eccentric strap 59 fitted above an eccentric 60 suitably keyed on a pump operating shaft 61. This shaft is suitably mounted for rotation in the .casing and is driven in synchronism with the engine to which the pump is applied, in a suitable manner, as by means of gearing indicated at 62. In the case of a pump for use with a four cylinder engine, for which the pump illustrated is intended, I provide four eccentrics 60 upon the shaft 61, these eccentrics being so related as to operate the plungers 56a inproper timed relation. Each plunger 56a has'associated therewith the suction and spill valves and 42, respectively,

' tappet is designated 64, and it is secured in adjustment by a jam nut 65, or in any other suitable manner.- The suction valve operating levers, four in number, are rockably mounted upon a supporting rod 66 which is adjustably supported, in a manner to be described, in the endwalls of casing 1. -Arm 63 is provided, at the lower end thereof, with a roller 67 which contacts the peripheral surface of a cam 68 keyed on shaft 61 at one side of and closely adjacent eccentric 60. This roller 67 is held in contact with its cooperating cam by an expansion coil spring 68a, the inner end of which seats about a stud 69 carried by arm 63 and bears against this arm. The outer end, portion of the spring 68 seats in a recess 70 provided in the inner end of as screw plug 71 which screws through a boss 72 of casing 1, this plug being secured in adjustment by a jam nut o. In

the rotation of shaft 61, arm 63 is actuated by cam 68 so as to cause opening and closlng of valve 30 in proper timed relation to the operation of spill valve 42 and the plunger 56.

' Spill valve 42 is actuated by a rock lever comprisin upper and lower arms 74 and 75, respective y, which are rigidly connected, as

by being formed integral. The levers for actuating the spill valves are rockably mounted on a supporting rod 76, which is suitably supported in the end walls of casin 1. Arm 74 is provided with a tappet 77 which screws in this arm and is secured in adjustment by a jam nut 78. Arm is provided, at its lower end, with a roller 79 which contacts the peripheral surface of a cam 80 suitably secured on shaft 61, as by means of a key 81. An expansion coil spring 82 serves to hold roller 78 in contact with its cam 80 in the same manner as spring 68a holds roller 67 in contact with its associated cam.

It is'desirable that means be provided for adjusting, within limits, the extent of opening of the suction and spill valves, and thereby regulating the measured quantity of oil which is supplied to the tube 22, and thence to the injection nozzle'of the engine, under pressure from the pump. For adjusting the opening of the spill valve 42, I provide a plate 82 which is disposed between tappet 77 and the lower end of valve stem 47, this plate decreasing in thickness from its upper end so as to provide, in effect, a wedge element- The plate 82' is provided, at the upper end thereof, with an 'eye 83 which receives a rod 84 secured in the lower ends of arms 85, the upper ends of which are secured upon a shaft 86 rockably mounted in bracket 52. Eye 83 is of materially greater interior diameter than the diameter of rod 84 so as to provide a loose connection between this rod and the plate 82.- A yoke 87 of inverted U-shape is secured upon rod 84 and straddles eye 83. This yoke has secured thereto a leaf spring 88 which bears upon eye 83 so as toavoid objectionable looseness or play between this eye and rod 84, while permitting proper relative movement of plate 82 in the operation of the valve42. An adjusting lever 89 is secured upon one end of shaft 86 and extends up-' wardly through a slot 90 in cover 2 of the 'pump casing. An eye bolt 91 is adjustably secured in this lever by a nut 92, and slidably receives a short rod 93 suitably secured in a,

standard 94projecting upwardly from cover 2. This provides simple and efficient means for securing the lever 89 in adjustment. By rocking shaft 86 in proper direction, the plate 82 is adjusted between valve stem 47 and tappet 77 so as to vary the extent of opening, and to a certain extent the timing, of the spill valve 42. In the pump illustrated, there are four spill'valves and, consequently, four plates 82, these plates being adjusted simultaneously by means of the shaft 86 and associated parts.

Referring more particularly to Figures 5 and 6, I provide rod 66 with an eccentric 95 adjacent each end thereof, these eccentrics being suitably mounted for turning in either direction in the end walls of easing 1.. An

adjusting lever 96 is secured on the rearward end of rod 66 and is provided with an arcuate slot 97 disposed approximately concentric with the eccentric 95. This slot receives a stud 98 secured in the end wall of the casing, and a nut 99 screws onto this stud and coacts therewith for securing the lever 96 in adj ustment. By turning rod 66, by means of lever 96, the eccentrics 95 are turned and serve to adjust rod 66 toward or away from the plunger 56. This varies, to a certain extent, the tim ing and the extent of opening of the suction valve 30. In the pump illustrated there are four of these valves and the levers .for actuating the same are adjusted simultaneously. A stop collar 100 is suitably secured upon the forward end of rod 66 and cooperates with lever 96 to hold this rod against endwise movement. As will be noted more clearly from Figure ,1, suitable spacing collars 101 are mounted upon the rod 76 between the levers for actuating the spill valves, these collars serving to hold these levers in proper. spaced relation and against endwise movement. The levers for actuating the suction valves are held .in proper spaced relation upon the rod 66 in the same manner.

- Referring more particularly to Figure 2 it will be noted that the center or axis a of shaft 61 is disposed to one side of the axis b-.'b of plunger 56a. 'It will also be noted that the axis or center 0 of eccentric60 is so disposed that it falls on the line of the axis b?) of plunger 5611 when point 11 on the periphery of the eccentric 60, and which is the most remote point of the eccentric from axis a of the shaft, is in the horizontal plane'of axis a on the up stroke of the plunger. This particular relation between the shaft and the eccentric and the plunger is important. By this means substantially all side pressure of the plunger 56a on its barrel 55, and the bending forces acting on the part of the plungsible to greatly reduce the size of the pump,

er which projects below barrel 55, are practically eliminated during the high pressure in jection period. The resulting increase in an gularity of the eccentric strap 59 during the downward stroke does not cause undesirable side pressures, because the pump is then operating at relatively insignificant pressures. This construction greatly reduces binding of the plunger, and wear, which renders it pcs since it is practicable to use a much shorter plunger and eccentric strap than heretofore ,and all necessity of using a crosshead, as in injection pumps of present construction, is

" avoided. Preferably, in practice, the dis tance between axis a of'shaft 61 and axis 0 of eccentric 60 is greater than that'shown, and may approximate the radius of the eccentric, though this is not essential and the construction illustrated operates in a satisfactory manner.

Referring more particularly to the diagram of Figure 3, the cams 68 and and the eccentric 60 are so proportioned and related that both the suction valve 30 and the spill valve 42 are closed during travel of point d of the eccentric through an arc of 9 extending from 5 below the position of this point in Figure 2 to 4 above the position of point (l in Figure 2. This means that the valves 30 and 42 are closed for a predeterminedperiod in the up stroke of plunger 560 during which the plunger is moving upwardly at its greatest speed.

This follows from the fact that when point d of the eccentric is in the position of Figure 2, it is in its most remote position from axis bb of plunger 56a during the up stroke of the plunger. It is also noted, as previously pointed out, that during this portion of the the pressure portion of its up stroke is avoid ed. Also, by having the valves closed durin the time that the plunger is moving upwar 1y at its greatest speed, I assure that an adequate supply of fuel will be injected into the engine during the short time available for injection of the fuel.

The valves 30 and 42 are so timed that the suction valve 30 opens 5 in advance of closing of the spill valve 42, and cam 68 is so shaped and proportioned that valve 30 remains open through an arc of 270. This valve closes at a point 5 below the position ofpoint d, shown in Figure 2, that is, immediately prior to the effective pressure stroke of plunger 56a. The plunger then moves upwardlv during travel of the eccentric 60 in an arc of 9, that is, during travel of point d from a position 5 below that illustrated in Figure 2 to a position 4 above the position of Figure 2, during which time the spill valve 42 remains close During this effective pressure. stroke of, plunger 56a, the oil displaced by the plunger is discharged under pressure through'port 14, unseating valve 15, and flows through tube 22, being injected into the engine, from the injection nozzle, in a known manner. Cam 80 cam 80 holding the spill valve open during travel of this cam through an arc of 86.

During the continued upward movement of the plunger 56a, the oil displaced thereby is discharged through space 46, port 45, channel 44 and duct 49 into the passage6, from which it flows through the return tube 10a. As previously noted, the suction valve 30 opens 5 rior to closing of the spill valve and, at this time,'a certain amount of oil will ruary 13,

be forced out of chamber 9, by plunger 56, through the passage 26, space 31, port 32, channel 33 and duct 40 into the foaming passage 8. This oil will be injected into the passage 8, instead of into the passage 7, due to the fact that it will follow the path of least resistance into passage 8 in preference to changing its direction of travel so as to enter the duct 40 and fiowinto passage 7 This is advantageous as the oil injected from-chamber 9 into the oil in passage 26 and adjacent passages and spaces, causes foaming and, in order to assure accurate operation of the .pump and the supply of accurately measured quantities of fuel to the tube 22, it is necessary that bubbles, such as those produced by foaming, be prevented from entering the pump chamber.

By providing the passage 8, I assure that any foam which is formed will collect in the upper portion of this passage and will not enter the pump chamber. Any foam which may be formed in the passage 6 and associated ducts and passages will be removed from this passage by the oil discharged therefrom and, therefore, will not enter the chamber. The means for preventing the foam from entering the pump chamber is disclosed more fully in my copending application for Fuel supply system, Serial No. 428,013, filed Feb 1930, and need not be further illustrated nor described here.

In the copending application of James B. Fisher and Max Hofmann, for Injection engine, Serial No. 413,303, filed December 11,

1929, there is disclosed an engine and associated means whereby the engine is warmed up on the Otto cycle and is thereafter operated on the Diesel cycle. Insuch engine, each injection nozzle is provided with an outlet tube having therein a valve which, when open,-

permits the oil to escape from the nozzle and other source of supply to which tube 9a is connected. In the event the outlet tube 102 is not used, this tube may be replaced by a screw plug for closing the end of passage 8.

What I claim is:

In a fuel pump having a pump chamber and inlet and outlet passages opening into the chamber at opposite sides thereof, a pump barrel opening into the chamber between said passages, a plunger operating in the barrel, valves controlling the passages, yielding means urging the valves closed, rocker levers for opening the valves, an operating shaft below the plunger and eccentric thereto, an eccentric secured on the shaft and so related thereto that its axis is subsantially in the plan of the axis of the plunger when the point on the periphery of the eccentric most remote from the axis of the shaft is in the horizontal plane of the axis of. said shaft during the instroke of the plunger, operating connections between the eccentric and the plunger, cams on the shaft for actuating said levers and timed to close both valves during travel of said point on the eccentric a prede termined distance beyond said horizontal plane, said cams acting to open the valves upon completion of such travel of said point on the eccentric, and an injectiontube communicating with the pump chamber.

In witness whereof, I hereunto subscribe my name this 6th day of December, 1929.

MAX HOFMANN.

return to an oil supply tank, thus preventing operation of the injection nozzle. During the warming up period, when operating on the Otto cycle, the valve referred to of each nozzle is open, and when operating on the Diesel cycle suchvalves arev closed, and the nozzles operate to inject fuel into the combustion chambers of the cylinders in a man- 'ner well understood by those skilled inthe art.

In Figure 4, I haveshown an outlet tube 102 connected to passage 8 in a suitable manner. This tube may lead from'valve controlled means for returning to passage 8 oil which is delivered by the pump to an injection device, such as an injection nozzle of an engine with which the pump is associated.

Upon establishment. of communication between tube 102 and the injection nozzle, or

other device to which oil is delivered by the pump, the oil is returned to passage 8 and flows through ducts 39 and 40 into passage 7 and thence, through tube 9a, to the tank or 

